Segment Information (Summary of Segment Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Summary of segment income
Segment income	$ 38,585	$ 39,408	$ 73,746	$ 77,166
Imaging [Member]
Summary of segment income
Segment income	38,311	37,528	73,474	76,033
Radiation Oncology [Member]
Summary of segment income
Segment income	9,121	9,800	16,806	17,506
Corporate / Other [Member]
Summary of segment income
Segment income	$ (8,847)	$ (7,920)	$ (16,534)	$ (16,373)